Global Cloudiness and Cloud Top Information from AVHRR in the 42-Year CLARA-A3 Climate Data Record Covering the Period 1979–2020
Round 1
Reviewer 1 Report
See the attachment
Comments for author File: 
Comments.pdf
Author Response
We thank the reviewer for the very positive review and the judgement that the manuscript can be published in present form. We have, however, made some modifications as a response to other reviewer's opinions.
Reviewer 2 Report
Overall, the paper provides usefu information about the quality and improvements in satellite data for cloud cover and depth. The paper is accepable for publication with attention to minor points:
1.Table 1 and 2 are statements Lines 250-252 correct for bias?
2.L 365 and 378 ref should be numerical not date
3. Figure 5 might state pressure units
4. Line 573 might spell out ANN fo clarity.
Author Response
Please see the attached file.
Author Response File: Author Response.pdf
Reviewer 3 Report
Review of the manuscript “Global cloudiness and cloud top information from AVHRR in the 42-year CLARA-A3 climate data record covering the period 1979-2020”, by Karlsson et al.
The role of clouds in the climate formation is undoubtedly major, they regulate the net radiation of the earth’s surface by modifying both incoming shortwave and outgoing longwave radiation. Clouds are also part of the water cycle, and they are responsible for the redistribution of heat in the atmosphere. Since their distribution is not continuous, the use of remote sensing techniques is the only way to study clouds. Although many passive satellite-borne instruments are in operation, the cloud data they provide are uncertain and must be validated against that retrieved from active instruments. The authors of the manuscript investigate the quality of cloud fractional cover and cloud top height products provided by the latest CLARA-A3 CDR and demonstrate its improvements in thin clouds detection by comparison against its predecessor and other CDRs. Trends and spatial patterns of the cloudiness parameters are also included in the study. A new validation metric (Cloud Detection Sensitivity) is introduced to describe cloud detection performance. The foregoing, I believe that this work will be of interest to a wide range of readers, and I recommend that it be published. Before that, some minor comments should be considered.
Minor comments:
1. Validation scores for CLARA-A3 stated in tab. 1 and 3 are calculated for 2010, while those for CLARA-A2 (tab.2 and 4) are based on ten-year period (2006-2015). Does the shown improvement remain if only 2010 data are used in CLARA-A2 validation? Do conclusions depend on matchup tolerance with CALIOP (three minutes for CLARA-A2 and five for CLARA-A3)?
2. It should be indicated if the trends presented in tab.7 are statistically significant or not.
3. Start of new sentence need to be capitalized (lines 16, 21, 133, 305)
Author Response
Please see the attached file.
Author Response File: Author Response.pdf
